Abstract
The Taiwanese people are composed of diverse indigenous populations and the Taiwanese Han. About 95% of the Taiwanese identify themselves as Taiwanese Han, but this may not be a homogeneous population because they migrated to the island from various regions of continental East Asia over a period of 400 years. Little is known about the underlying patterns of genetic ancestry, population admixture, and evolutionary adaptation in the Taiwanese Han people. Here, we analyzed the whole-genome single-nucleotide polymorphism genotyping data from 14,401 individuals of Taiwanese Han collected by the Taiwan Biobank and the whole-genome sequencing data for a subset of 772 people. We detected four major genetic ancestries with distinct geographic distributions (i.e., Northern, Southeastern, Japonic, and Island Southeast Asian ancestries) and signatures of population mixture contributing to the genomes of Taiwanese Han. We further scanned for signatures of positive natural selection that caused unusually long-range haplotypes and elevations of hitchhiked variants. As a result, we identified 16 candidate loci in which selection signals can be unambiguously localized at five single genes:
CTNNA2,
LRP1B,
CSNK1G3,
ASTN2, and
NEO1. Statistical associations were examined in 16 metabolic-related traits to further elucidate the functional effects of each candidate gene. All five genes appear to have pleiotropic connections to various types of disease susceptibility and significant associations with at least one metabolic-related trait. Together, our results provide critical insights for understanding the evolutionary history and adaption of the Taiwanese Han population.
Introduction
Disease susceptibility differs greatly between populations and appears to be correlated with human population history (Chen et al. 2012; Corona et al. 2013). However, owing to the complex history of human migration, most contemporary populations are genetically admixed, which could complicate the efforts of genetic profiling for susceptibility to diseases (Gravel 2012; Kidd et al. 2012; Marnetto et al. 2020). Therefore, understanding the genetic ancestry, population substructure, and migration history of people who live in the same geographic region may allow us to better characterize the admixed ancestry for each individual genome, providing critical information to facilitate genome-wide association studies for mapping disease-causing variants. Disease susceptibility may also arise as side effects of evolutionary adaptation. Under a certain selection pressure (e.g., malaria), genetic adaptation could increase an individuals’ fitness in terms of survival or reproductive success, but this could sometimes be accompanied with the cost of the carriers’ health (Haldane 1932). Sickle-cell anemia, thalassemia, and APOL1-mediated kidney diseases are among the most noticeable examples in which carriers of the respective disease-causing variants confer protective effects against parasitic infection (Kwiatkowski 2005; Weatherall 2008; Genovese et al. 2010; Ko et al. 2012, 2013). Therefore, detection of genomic signatures of evolutionary adaptation provides an alternative approach to shed light on the biological mechanisms underlying disease susceptibility (Lachance and Tishkoff 2013; Vasseur and Quintana-Murci 2013).
Taiwan is home to a diversity of human ethnic groups that can be roughly grouped into three major populations. Taiwanese Han people are the descendants of early immigrants (mainly Minnan and Hakka) who migrated from Southern China in the last 400 years and were recently joined by many immigrants from various geographic areas of China at the end of World War II in 1945 (Dittmer 2004). The second major group contains 16 officially recognized indigenous populations, representing 2.3% of the total population in Taiwan. These indigenous tribes harbor rich genetic diversity and have been considered as the ancestral lineages of Austronesian-speaking people (Trejaut et al. 2005; Soares et al. 2011; Ko et al. 2014; Lipson et al. 2014; Trejaut et al. 2014; Chang, Liu, et al. 2015; Soares et al. 2016). Finally, the third group, Taiwan plain aborigines (Pingpu), includes many tribes that previously inhabited plains across the island of Taiwan. Although they are thought to be descendants of Austronesian-speaking people, most of these tribes may have admixed with the Taiwanese Han people (Trejaut et al. 2005, 2014). However, the extent of contribution of genetic diversity from the Pingpu aborigines to the Taiwanese Han, as well as the degree of population mixture between the current Taiwanese Han and indigenous populations, is unclear.
Re: Russia, US, Ukraine, and the Future
Originally Posted by Sir Adrian
is just as silly as blaming Middle Eastern nations for border conflicts caused by colonial powers carving up the region with 0 regard to ethnic or religious divides after WW1.
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